Vacuum chuck for ophthalmic lens finishing machinery

ABSTRACT

A vacuum chucking system for securing and holding an ophthalmic lens blank without the requirement of forming a block to a surface thereof.

United States Patent 1 1 v .1 1 3,794,314

, [73] Assignee: Coburn Optical Industries, Inc.,

Coburn et a1. 1 Feb. 26, 1974 [5 1 VACUUM CHUCK FOR OPHTHALMIC 1,503,390 7/1924 Tenney 269/21 x S FINISHING MACHINERY 2,688,220 9/1954 Boutell 51/235 3,015,196 1/1962 Campbell 51/284 [75] Inventors: Orin W. Coburn; Joe D. Stith, both 3,461,622 8/1969 Rayford 51 235 X ofMuskogee, Okla. 2,545,448 4/1951 Clement 51/284 X F APPLl Muskogee, Okla QREIGN PATENTS 0R CATIONS 1,014,564 6/1952 France 279/3 22 I Filed: Jan. 13, 1972 v 1 1211 Appl. No: 217,469 Primary Examiner James L. Jones, Jr. Assistant'Examiner-J. T; Zatarga 52 us. c1. ..,.....'269/21, 51/216 LP, 51/217 L, AmmeY, Byme 51/235, 51 /284, 279/3 51 1m.c1 B25b 11/00 [58] Field 0fSearch..269/2l; 51/235, 216 LP, 217 L, 1 1 RA A vacuum chucking system for securing and holding an ophthalmic lens blank without the requir er'nent of, 1 5 ,Reterenc-esvclted I forming a block to a surface thereof.

' UNITED STATES PATENTS 904,679 11/1908 Bruto'n 279/3 1 Claim, 8 Drawing Figures I I I I 1 1 Y 5 I y 44 r 42 34 VACUUM CHUCK FOR OPI-ITHALMICLENS FINISHING MACHINERY of pitch or the like. Another common method is forming a metallic block of a low-melting point alloy. In each of these methods, of course, the lens blank must be oriented with respect to the'block and after finishing 7 common lens blocking techniques of the prior art. In

the block must be removed and the lens cleaned. The

pitch or alloy must be recovered for economic reasons.

A principal objective of this invention is to overcome the disadvantages of the prior-art blocking methods by securing the lens to a block by way of a vacuum. The block itself is provided with means for orienting the lens therewith and is equipped with all other features common to and considered necessary for a lens block.

Another important objective of this invention is to provide a vacuum system for securing lens blanks which is readily used with fining, polishing, beveling and generating equipment now on the marketplace.

Another important objective of this invention is to provide a lens block having a flexible opening-adapted to receive one surface of a lens blank wherein this surface becomes a wall of a vacuum-cavity which is used to secure the lens to the block.

A still further objective of this invention is to provide a lens blocking system in which a lens block is provided having hardened steel inserts for lens equipment drive pins and vacuum drawn via flexible tubing so that the apparatus for the vacuum source will not hamper or otherwise interfere with the movement necessary to lens fining, polishing, and surface generation.

Another objective of this invention'is to provide a blocking system which does not require separate blocking equipment or the requirement for melting pitch or alloy.

A still further objective of the invention is to provide a blocking system which utilizes a vacuum source of a type which is oftentimes already available in a lens finishing laboratory.

These and other objects of the invention will become more apparent to those skilled in the art by reference to the following detailed description when viewed in light of the accompanying drawings wherein:

FIG. 1 is an elevation view partially in section of a prior art block;

FIG. 2 is a bottom plan view of the unit as shown in FIG. 1;

FIG. 3 is a plan view of a first embodiment of this in- 4 vention;

this method, a lens L is secured to a block 10 by way of an adhesive 12. The member 10 can be steel or a formed-in-place metallic or plastic block. The block is circular for ready reception in chucking equipment. One of the surfaces is formed with detents or depressions l6 and 18 and oftentimes with a center detent 20. These detents oftentimes receive steel-hardened inserts to increase the longevity of the block.

A first embodiment of a block of this invention is shown in FIGS. 3 through 7. The blank will again be indicated by the letter L. As shown in FIGS. 3 and 4, a steel block 30 is provided having a circular boss or orienting protrusion 32 along one surface thereof. Its exterior cylindrical surface is indicated by the numeral 33. The other surface of the block is formed with a dishshaped depression 34 which is circumscribed by a rim 36. As shown in FIG. 3 the rim 36, immediately below its top edge 38, is formed with an inwardly tapered edge 40.which receives the lens blank L. The tapered edge 40 provides a shoulder for the lens blank. Immediately below the shoulder 40 an annular depression 42 receives a resilient plastic or rubber gasket member 44. As will be described more fully hereinafter, the gasket 44, together with the lens blank L and the depression 34 provides a sealed vacuum chamber 46.

A fitting 48 extends outwardly from the peripheral surface 33 and leads to a vacuum source 50 via a flexible tubing 52. The block member 30 is formed with a passageway 54 leading to the vacuum source via fitting 48 and the flexible tubing 52.

The upper surface 38 of the rim 36 has indicia or alignment marks 56 and 58. These alignment marks are matched with indicia previously applied to the lens blank L. The marks'are so placed onthe lens blank by conventional means such as a marking pen or layout marker. 8

In operation, an equipment operator places the lens L as shown in FIG. 6 while orienting the alignment marks. A switch activates the vacuum source 50 which causes chamber 46 to become a sealed vacuum holder. The axial position of the lens is accurately .determined because the lens blank will engage the surface 40. The rim 36 is notched at 56 for alignment with the lens generating chucking equipment. I

A second embodiment of the invention is shownin FIGS. 7 and 8. Here the blocking member has the vacuum source fitting 74 entering the center of the depression with hardened steel inlets and 72'for drive pins. Note that the rim 38 has indicia marks for alignment with the base curve of the lens. The center positioning of fitting 74 reduces vibrations when the block is used with polishing and fining machines of the type mentioned in assignee's co-pending application, Ser. No. 169,224, filed Aug. 5, 1971, entitled POLISHER- FINER MACHINE.

In a general manner, while there has been disclosed an effective and efficient embodiments of the invention, it should be well understood that the invention is not limited to such embodiments as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the optical orientation of said blank during lens finishing processing, that improvement comprising ery secured in said groove and extending inwardly to define an opening having a diameter less than the diameter of saidupper surface, a vacuum source,

conduit system communicating said vacuum source with said cavity,

said conduit system including a bore through said chucking member,

a flexible hose communicating said bore and said vacuum source, whereby when a lens blank is placed in engagement with said gasket and said vacuum source draws a vacuum in said enclosed cavity, said lens blank seals against said gasket and is securely held to said chucking member. 

1. In a vacuum chucking system for securing a lens blank of a type having indicia thereon to indicate the optical orientation of said blank during lens finishing processing, that improvement comprising a chucking member having a shallow depression defined by a base portion and a peripheral rim extending upwardly about said base and said rim having inner and outer surfaces terminated by an upper annular surface said upper surface of said peripheral rim having orienting indicia thereon, an inwardly and downwardly tapered edge extending from said inner surface a short distance from said upper surface and providing a shoulder for the lens blank an annular groove formed immediately below said tapered edge, a Flat, annular, flexible gasket having its outer periphery secured in said groove and extending inwardly to define an opening having a diameter less than the diameter of said upper surface, a vacuum source, conduit system communicating said vacuum source with said cavity, said conduit system including a bore through said chucking member, a flexible hose communicating said bore and said vacuum source, whereby when a lens blank is placed in engagement with said gasket and said vacuum source draws a vacuum in said enclosed cavity, said lens blank seals against said gasket and is securely held to said chucking member. 